Liquid crystal display element

ABSTRACT

A liquid crystal display element of a dot matrix structure comprises a liquid crystal panel constituted by a first substrate equipped with a first electrode, a second substrate equipped with a second electrode, and a liquid crystal layer furnished between the first substrate and the second substrate, wherein the liquid crystal layer comprises a support column of a wall structure possessing adhesiveness, wherein a part of each of the support columns has a wider part.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a continuation of PCT application ofPCT/JP2005/012792, which was filed on Jul. 11, 2005.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a liquid crystal display element of adot matrix system, and in particular to one excelling in flexibility.

2. Description of the Related Art

The rapid popularization of a type of electronic paper capable ofretaining a display without a power source and enabling the electronicrewriting of the display content is predicted to happen in the nearfuture. Research is in progress to find a type of electronic paper foraccomplishing a reflective display that is gentle to the eyes so as notto tire them and that consumes an extremely low power amount, enabling amemory display to remain even after the power is cut off and enabling itto have a display body that is thin and flexible like paper. Conceivableapplications of an electronic paper like this include, for example,electronic books, electronic newspapers, and electronic posters.

Electronic paper is categorized into an electrophoresis method, atwisted ball method, a liquid crystal display, an organicelectroluminescence (EL) display, et cetera, depending on the differenceof display method.

The electrophoresis method is a method for moving charged particles inthe air or liquid. The twisted ball method is a method for rotatingcharged particles colored in two colors. The organic electroluminescence(EL) display is a self light-emitting display configured to sandwich aplurality of thin films made from an organic material by negative andpositive electrodes. The liquid crystal display (LCD) is a non-selfluminescent display configured to sandwich liquid crystal layersrespectively by pixel electrodes and opposed electrodes.

Research and development of electronic paper made from an LCD is inprogress, employing a selectively reflective cholesteric liquid crystalachieving bi-stability by utilizing an interferential reflection of aliquid crystal layer. Here, bi-stability means that a liquid crystal isstable in two different orientation states and a cholesteric liquidcrystal is able to retain two stability states, i.e., planer andfocal-conic states, for a long time even after the electric field isremoved. In the cholesteric liquid crystal, an incident light isreflected in interference during the planer state and the incident lightis transmitted during the focal-conic state. Therefore, a contrast oflight can be displayed by using the selective reflection of an incidentlight on the liquid crystal layer in a liquid crystal panel using acholesteric liquid crystal for the liquid crystal layer, therebyeliminating a necessity of a deflection plate. Note that the cholestericliquid crystal is also called a chiral nematic liquid crystal.

A cholesteric liquid crystal that reflects a color via the interferenceof a liquid crystal is overwhelmingly advantageous in a color display ofa liquid crystal display and therefore a color display is possible justby layering. Because of this, a liquid display system employing thecholesteric liquid crystal (which is called a “cholesteric liquidcrystal system” herein for convenience) is overwhelmingly advantageousas compared to other systems, such as the electrophoresis method, interms of color display. Other systems require a color filterdivisionally colored in three colors for each pixel, causing thebrightness to be one third that of the cholesteric liquid crystal.Because of this, the other systems are faced with a big obstacle in theimprovement of the brightness for electronic paper.

As described above, while the cholesteric liquid crystal is a strongcontender for electronic paper, the biggest problem has been thecreation of physical flexibility that is a characteristic of electronicpaper.

An LCD element requires a uniform cell with a gap of severalmicrometers, and a cell is formed by sandwiching a liquid crystal layerseveral micrometers thick where is between the top and bottom glasssubstrates. In some common liquid crystal panels of a twisted nematic(TN) type and a super twisted nematic (STN) type, an LCD element using afilm substrate (i.e., a plastic liquid crystal) made from a transparentspecial resin has already been implemented. The plastic liquid crystalcan be made thinner and of a lighter weight than a liquid crystal usinga glass substrate, and further excels in durability and strength againstbending. Therefore, the plastic liquid crystal is freely bendable like apaper and is accordingly suitable for electronic paper.

To accomplish a uniform cell gap in a liquid crystal panel of the TN orSTN type, arraying support spacers 5 of a column form in the fourcorners of a pixel as shown in FIG. 1 has conventionally been proposed.

The liquid crystal panel of the TN type or STN type shown in FIG. 1 hasarrayed the support spacers 5 in positions corresponding to grid pointsof a black matrix 6 on an upper surface substrate 2, wherein a liquidcrystal layer is placed between the upper surface substrate 2 and alower surface substrate 1 that are maintained at an equal distance fromeach other by the support spacers 5.

The support spacers 5 are featured on the lower surface substrate 1 onwhich, in addition to the support spacers 5, a seal member 3 foradhering between the upper surface substrate 2 and lower surfacesubstrate 1 is featured. The seal member 3 is an adhesive member formedby printing or such, with the center of one side 3 a being featured withan opening part, of which both ends are extended to form an injectionhole 4. That is, the configuration is such that a part of the sealmember 3 constitutes the injection hole 4 so as to inject a liquidcrystal in the area enclosed by the seal member 3.

The top surface of the lower surface substrate 1 and the bottom surfaceof the upper surface substrate 2 are respectively featured with aplurality of transparent column electrodes (not shown in any drawingherein) and with a plurality of transparent row electrodes (not shown inany drawing herein), perpendicularly crossing the column electrodes.Also, the bottom surface of the upper surface substrate 2 is featuredwith a black matrix 6. In the LCD element configured, as describedabove, using a selectively reflective cholesteric liquid crystal in theliquid crystal layer, the part between pixels in which an electrode isnot featured in the upper or lower opposed position is continuously lit.Consequently, the black matrix 6 is equipped for improving the contrastof a pixel by preventing it from being continuously lit. As for themethod for forming circular or rectangular columns such as the supportspacer 5, a forming method using photolithography has been proposed.Further, a liquid crystal display element in which the spacers are in across form have proposed.

In the case of a display panel of a selectively reflective cholestericliquid crystal system, however, the mere accomplishment of a uniformcell gap cannot provide a material with flexibility. The reason for thisis that the liquid crystal is a fluid so that the bending of a liquidcrystal panel and/or the pressing of the display surface moves theliquid crystal forced by the added force of such action(s), resulting ina change in the display states. In the case of displaying a liquidcrystal panel using the TN type or STN type, a change of display statescan be reverted back to the original state because it is continuouslydriven electrically. In the cholesteric liquid crystal possessing adisplay memory property, however, the display cannot be reverted back tothe original until it is re-driven.

An example of a method for featuring support spacers as shown in FIG. 1for an element panel of the cholesteric liquid crystal is disclosed; aliquid crystal light modulation display element, however, mainly aims atsecuring uniformity in a cell gap therefore the liquid crystal lightmodulation display element is not configured to retain a memory propertyof a display element panel of a cholesteric liquid crystal system whenperforming operations such as bending a liquid crystal panel and/orpressing the display surface.

In the meantime, while the conventionally known capsule construction ofa liquid crystal provides the effect of preventing a change in displaystates, it is faced with the problem of reduced contrast due to lightdiffusion noise from the capsule wall and that of increased drivevoltage due to the capsule wall, thus resulting in a low possibility ofimplementing it as a commercial product. Particularly, such a lightdiffusion noise is a big problem for an LCD panel displaying colorhaving a layered structure of liquid crystal layers for each of thecolors red, green and blue (RGB).

With these backgrounds, the biggest problem has been implementing an LCDelement having a structure that will not allow a change of display evenif the electronic paper is pressed or bent in order to be able to applya selectively reflective cholesteric liquid crystal to electronic paper.

The present applicant of the present invention has proposed an LCDelement of the comprisal shown in FIGS. 2 through 4 as an LCD element ofa cholesteric liquid crystal applicable to electronic paper.

FIG. 2 is a diagonal view diagram showing an overall three-dimensionalconfiguration of the LCD element; FIG. 3 is a plain view diagram showinga positional relationship between support columns 15 and a matrixelectrode for the LCD element; FIG. 4A is an overall layout pattern ofthe support columns 15 featured on the lower surface substrate 1; andFIG. 4B is a cross-sectional diagram of the column 15 in the horizontaldirection.

The configuration is such that an adhesive support spacer 15 is formedto be a wall face structure body in approximately the form of a crossand gaps (i.e., opening parts) for injecting liquid crystal into thepixels are equipped between adjacent support spacers (i.e., columns) 15as shown in FIG. 2. Also equipped is a wall face structure body 17(which is called a wall face seal structure body 17 hereinafter forconvenience) on the outer circumference of the surface of the lowersurface substrate 1. The support column 15 and wall face seal structurebody 17 may be made from the same material, making it possible to formthem in the same photolithography process.

In the liquid crystal layer, a portion in which the column electrode(i.e., the signal electrode) 21 and row electrode (i.e., the scanelectrode) 23 cross with each other constitutes a pixel 25, with thefour corners thereof being equipped with support columns 15,respectively. A seal member 13 is placed on the outside of the sealstructure body 17 with a prescribed distance apart therefrom. Thenecessity of the seal member 13 is arbitrary. While the bottom surfaceof the upper surface substrate 2 is featured with a black matrix 6, theplurality of support columns 15 is similarly patterned as the blackmatrix 6 with the layout position in the vertical direction of thepattern almost overlapping with that of the black matrix 6, andtherefore it may be eliminated. Further, the support columns 15 arearrayed in the gap parts between the signal electrodes 21 and scanelectrodes 23 so as to make the opening ratio of the pixels 25 be themaximum, as shown in FIG. 3.

The present applicant has proposed an LCD element having a configurationin which two kinds of support columns 15 a and 15 b are placed on thelower surface substrate 1 in the pattern as shown in FIG. 5A by virtueof the aforementioned PCT/JP/2005/4925. The LCD element is configuredsuch that the support column 15 a shown in FIG. 5 B and the supportcolumn 15 b shown in FIG. 5C are placed alternately so as to makeadjacent columns between the individual scan electrodes 23 differentfrom each other.

Meanwhile, FIG. 6 is a diagram showing a plain view form of the wallface seal structure member 17 featured on the circumference of the lowersurface substrate 1 (i.e., in the inside of the seal member 13) of theLCD element proposed. The wall face seal structure member 17 is of thesame material as that of the support column 15 and is therefore formedsimultaneously in the same process of forming the support column 15.

A prototype modeling of a cholesteric LCD element of the structure shownin FIGS. 2 through 4, however, has uncovered the problem with the LCDelement as described in the following.

A fine and high-resolution display is desired for a display element,requiring a finer and smaller form of the electrode structure and wallface structure body (i.e., support columns 15). An electronic paper notusing a light source such as a backlight is a reflective displayelement, strongly requiring improvement in an opening ratio forincreasing the brightness (i.e., luminance) of the display.

In the aforementioned LCD display, a higher resolution was attempted bymaking the gap between electrodes be 10 to 30 micrometers and bynarrowing down the width of the support columns 15 in association withthe width of the gap, occurring the problem of the support column 15coming off in the development process of the photolithography process.

The LCD element of the electronic paper commonly uses a plastic film forthe substrate. When this is the case, a plastic surface of the substrateis exposed in the gap part between the electrodes on the substrate. Theelectrode uses a transparent electrode material such as indium tin oxide(ITO). The wall face structure body placed in the gap part between theelectrodes has a low degree of adhesion to the plastic surface. Ahigh-resolution pattern of the wall face structure body where theadhesion area size with the substrate 1 becomes small has a structureallowing easy detachment from the plastic surface. Because of this, itcan seem that detachment of the support column 15 has occurred.Furthermore, observation of the phenomenon of the detachment shows thatthe beginning of the detachment is at the tip part of the branch part ofthe support column 15 of the cross form.

Meanwhile, the wall face seal structure body 17 as shown in FIG. 6 hasconventionally been formed to be a few millimeters thick, inconsideration of durability. In order to achieve a high-resolution LCDelement, such a pattern must be formed finer and smaller, i.e., at ahigher resolution. If the pattern is formed at a higher resolution,however, detachment will occur more remarkably in the developmentprocess of a photolithography process for forming the support columns15. This is attributable to a decreased adhesiveness occurring as theseal structure body 17 of a line form becomes more slender.

The material of the wall face seal structure body 17 exerts the functionof making the upper and lower surface substrates adhere with each otheras a result of a pressurized heat treatment being applied. A reactiongas is generated in the process that the material becomes adhesive andhardened. Further, it has also been discovered that a large number ofair bubbles remain in the adhesion surface between the lower surfacesubstrate 1 and wall face seal structure member 17 due to the gas,causing an adhesion failure, which is a factor of the detachment.Furthermore, the remaining gas flows into the liquid crystal layer ofthe display part, and thus the remaining gas causes an occurrence of adisplay failure.

SUMMARY OF THE INVENTION

According to one aspect of the present invention, there is a liquidcrystal display element of a dot matrix structure including: a liquidcrystal panel constituted by a first substrate equipped with a firstelectrode, a second substrate equipped with a second electrode, and aliquid crystal layer furnished between the first substrate and thesecond substrate, wherein the liquid crystal layer comprises a supportcolumn of a wall structure possessing adhesiveness, wherein a part ofeach of the support columns has a wider part.

According to another aspect of the present invention, there is a liquidcrystal display element of a dot matrix structure including: a liquidcrystal panel comprising a first substrate equipped with a firstelectrode, a second substrate equipped with a second electrode, and aliquid crystal layer furnished between the first substrate and thesecond substrate, wherein the liquid crystal layer comprises a supportcolumn of a wall structure having a wider part in one part thereof andpossessing adhesiveness, and a seal structure body of a wall structurehaving a liquid crystal injection hole.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a block diagram showing a cell structure of an LCD element ofa conventional dot matrix structure accomplishing a uniform cell gap byusing support column spacers.

FIG. 2 is a block diagram showing an overall configuration of an LCDelement applying a selectively reflective cholesteric liquid crystal toelectronic paper.

FIG. 3 is a plain view diagram showing a placement pattern of supportcolumns equipped on a lower surface substrate of the LCD element shownin FIG. 2.

FIG. 4A is a partial enlargement diagram of a support column placementpattern of FIG. 3, and FIG. 4B is a diagram showing the form of thesupport column.

FIG. 5A is a diagram exemplifying a configuration of a placement patternof support columns in an LCD element applied to electronic paper, FIG.5B is a diagram showing a first support column formed on a substrate ofthe LCD element, and FIG. 5C is a diagram showing a second supportcolumn formed on the substrate of the LCD element.

FIG. 6 is a diagram showing a form of a seal structure body formed on asubstrate of the LCD element shown in FIG. 2.

FIG. 7A is a diagram showing a placement pattern of a support column ofan LCD element according to a first preferred embodiment of the presentinvention, and FIG. 7B is a diagram showing a form of the support columnof the LCD element according to the first embodiment.

FIG. 8 is a diagram showing a three-dimensional structure of the supportcolumn comprised by the LCD element of the first embodiment.

FIG. 9 is an A-A cross-section diagram of the LCD element of the firstembodiment shown in FIG. 7A.

FIG. 10A is a diagram showing a placement pattern of a support columnformed on a lower surface substrate of an LCD element according to asecond preferred embodiment of the present invention, FIG. 10B is adiagram showing a form of a first support column of the LCD elementaccording to the second embodiment, and FIG. 10C is a diagram showing aform of a second support column of the LCD element according to thesecond embodiment.

FIG. 11A is a diagram showing a placement pattern of a support columnformed on a lower surface substrate of an LCD element according to athird preferred embodiment of the present invention, FIG. 11B is adiagram showing a form of a first support column of the LCD elementaccording to the third embodiment, and FIG. 11C is a diagram showing aform of a second support column of the LCD element according to thethird embodiment.

FIG. 12A is a diagram showing a placement pattern of a support columnformed on a lower surface substrate of an LCD element according to afourth preferred embodiment of the present invention, FIG. 12B is adiagram showing a form of a first support column of the LCD elementaccording to the fourth embodiment, and FIG. 12C is a diagram showing aform of a second support column of the LCD element according to thefourth embodiment.

FIG. 13A is a diagram showing a placement pattern of a support columnformed on a lower surface substrate of an LCD element according to afifth preferred embodiment of the present invention, FIG. 13B is adiagram showing a form of a first support column of the LCD elementaccording to the fifth embodiment, and FIG. 13C is a diagram showing aform of a second support column of the LCD element according to thefifth embodiment.

FIG. 14A is a diagram showing a placement pattern of a support columnformed on a lower surface substrate of an LCD element according to asixth preferred embodiment of the present invention, FIG. 14B is adiagram showing a form of a first support column of the LCD elementaccording to the sixth embodiment, and FIG. 14C is a diagram showing aform of a second support column of the LCD element according to thesixth embodiment.

FIG. 15 is a diagram showing a seal structure body formed on a lowersurface substrate of an LCD element according to a seventh preferredembodiment of the present invention.

FIG. 16 is a partial enlargement diagram of a seal structure body of anLCD element according to an eighth preferred embodiment of the presentinvention.

FIG. 17 is a partial enlargement diagram of a seal structure body of anLCD element according to a ninth preferred embodiment of the presentinvention; and

FIG. 18 is a partial enlargement diagram of a seal structure body of anLCD element according to a tenth preferred embodiment of the presentinvention.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

The following is a description of the preferred embodiment of thepresent invention by referring to the accompanying drawings.

An LCD element according to the present embodiment is a dot matrix type(i.e., a dot matrix structure), the overall configuration of which isapproximately the same as that of the LCD element shown in FIG. 1. Thedifference between the LCD element according to the present embodimentand the conventional one shown in FIG. 1 is in the form of a wall facestructure formed on the lower surface substrate. Also different in someembodiments described later is the configuration of a seal structurebody of a wall face structure, in addition to the form of the supportcolumn.

In a dot matrix LCD element, a scan electrode is formed in the formationof stripes at equal intervals on a lower surface substrate, andtherefore the top surface (i.e., the resin surface) of the lower surfacesubstrate is exposed in the space between scan electrodes. The supportcolumns are formed between the scan electrodes, resulting in the supportcolumn contacting with the resin surface. The adhesive force of theresin surface is lower with the support column than with a surface ofthe scan electrode 43 (i.e., the scan electrode surface), which is acause for the column detaching in the development process of thephotolithography process forming the support column. Therefore, theembodiment described in the following is configured to thicken the tipor center part of the cross-formed branch, and the thickened part isformed so as to contact with a scan electrode surface, thereby makingthe support column be in close contact with the scan electrode surface.As a result, the configuration suppresses a detachment of the supportcolumn in the aforementioned development process.

The following is a description of a preferred embodiment applying thepresent invention to a dot matrix cholesteric LCD element.

[First Embodiment]

FIGS. 7 through 9 are a diagram showing a configuration of the LCDelement according to the first embodiment.

FIG. 7 is a diagram showing the form and placement pattern of a supportcolumn formed on the lower surface substrate of the LCD elementaccording to the present embodiment.

A support column 101 of a wall face structure according to the presentembodiment is configured to be shaped approximately like a cross, withall four branches thereof thicker at their tips. The support column 101is made from an adhesive material so as to function as a spacer as wellas shown in FIG. 7( b).

The support columns 101 are equipped on the four-sided circumference ofeach pixel 45 arrayed on a scan electrode 43 as shown in FIG. 7 (b). Twobranches of the support column 101 are formed between the adjacent twoscan electrodes 43.

FIG. 8 is a diagram showing a three-dimensional structure of the supportcolumn 101 comprised by the LCD element of the present embodiment,showing a support column 101 placed at an edge part of an LCD element.

The support column 101 is a wall face structure body of which the crosssection in the horizontal direction is shaped approximately like across, as shown in FIG. 8. The surface of a lower surface substrate(i.e., a first substrate) 31 has a plurality of scan electrodes (i.e.,first electrodes) 43 at equal intervals, and the two branches of thesupport column 101 are formed to be in contact with the lower surfacesubstrate 31 between the adjacent two scan electrodes 43. The other twobranches of the support column 101 are formed on the scan electrode 43.Since the tip of the support column 101 is thickened, the edge thereofon the scan electrode 43 side is formed on the scan electrode 43. Atransparent electrode material such as ITO is used for the electrode.

FIG. 9 is an A-A cross-sectional diagram of FIG. 7. The upper surface ofthe lower surface substrate 31 has a plurality of scan electrode 43 inequal intervals and also has the support columns 101 possessingadhesiveness between the adjacent scan electrodes 43. A plurality ofsignal electrodes (i.e., second electrodes) 41 are equipped so that thesignal electrodes 41 cross with the scan electrode 43 at right angleswhen viewed from above on an upper surface substrate (i.e., a secondsubstrate) 32 which is equipped opposite to the lower surface substrate31 (i.e., at the side of the lower surface substrate 31). The lowersurface substrate 31 and upper surface substrate 32 are both adhesivelyfixed onto the adhesive support columns 101 which, as spacers, maintaina prescribed distance between both of the substrates. The regionenclosed by the signal electrode 41, scan electrode 43 and supportcolumn 101 is injected with a liquid crystal, thus constituting a pixel45.

The support column 101 is formed between the scan electrodes 43 where asurface of the lower surface substrate 31 is exposed. As describedabove, the support column 101 that is an adhesive material has a higheradhesion force to the surface of the scan electrode 43 (noted as “scanelectrode surface” hereinafter) than to the surface of the lower surfacesubstrate 31.

The four branches of the support column 101 according to the presentembodiment are entirely or partly adhered to the scan electrode surfaceand therefore the adhesion area size between themselves and the scanelectrode surface is larger than the adhesion region between the supportcolumn 15 and the scan electrode surface, which is shown in FIG. 3, ofwhich the two branches have no adhesion with the scan electrode surface.By virtue of this, the support column 101 has a higher adhesion force tothe scan electrode than the support column 15 does to the scanelectrode. Also, an electrode material (e.g., ITO, et cetera) has ahigher adhesion force to the support column than a plastic film that isa substrate material does, and therefore the effect of preventing adetachment can be further improved in this aspect. As a result, it ispossible to suppress a situation in which the support column 101 isdetached from the lower surface substrate 31 in the development processof a photolithography process.

Meanwhile, the support column 101 overlaps with the electrode surfaces(i.e., the signal electrode 41 and scan electrode 43) only on the sidesof the branch and therefore the opening ratio of the pixel 45 of the LCDelement according to the present embodiment is a little lower than thatof the pixel 25 of the LCD element shown in FIG. 3.

Incidentally, the support column 101 according to the present embodimentis configured to be thicker at the tip part of the branches; the placewhere the area size of the branch is larger (when viewed from above thecolumn), however, can be arbitrarily determined to be anywhere betweenthe center and edge part of the column. To prevent detachment, however,a thickened tip part is most effective. Also, the thickened part isshown as a rectangular shape in the drawing, which is arbitrary; a roundshape may be used instead.

In the meantime, the spacer for the liquid crystal layer may use thesupport column 101 together with a conventional spherical spacer orcolumnar spacer. Parallel use with such a spacer can be commonly appliedto LCD elements according to all embodiments described below.

[Second Embodiment]

FIG. 10 is a diagram showing a configuration of a support column of anLCD element according to a second preferred embodiment. The presentembodiment is configured to be capable of better improving the openingratio of a pixel than the support column 101 of the LCD elementaccording to the first embodiment described above is capable of doing.

The present embodiment is configured to place, as a support column, twosupport columns 102 a and 102 b with wall face structures shown in FIGS.10 (b) and (c) as shown in FIG. 10 (a). The support column 102 a isconfigured to make thicker the tip part of the branch that is parallelwith the longitudinal direction of the scan electrode 43. The supportcolumn 102 b is configured to make thicker the tip part of the branchthat is perpendicular to the longitudinal direction of the scanelectrode 43.

The present embodiment is configured to place these two support columns102 a and 102 b alternately as shown in FIG. 10 (a). In this event, thesupport columns 102 a and 102 b are alternately placed in the up/downdirection (i.e., the longitudinal direction of the signal electrode) aswell as the left/right direction (i.e., the longitudinal direction ofthe scan electrode 43).

Such a placement makes it possible to maintain the form of the pixel 45nearly square in the case of rotating the support column 102 a andsupport columns 102 b ninety degrees each.

If a pixel is rectangular, the display of a straight line has differentline widths in the vertical and horizontal directions. Therefore, it ispreferable that the pixel shape be closer to a square. Because of this,the present embodiment excels in the displaying of straight lines.

The present embodiment is configured such that the adhesion areas of thesupport columns 102 a and 102 b, including the scan electrode surface,are smaller than that of the support column 101 of the first embodiment,and therefore the adhesion force to the scan electrode 43 is smallerthan that of the support column 101. However, the opening ratio of thepixel 45 is larger in the present embodiment. The opening ratio of thepixel 45 is only slightly lower than that of the pixel 25 shown in FIG.3.

[Third Embodiment]

FIG. 11 is a diagram showing a configuration of a support column of anLCD element according to a third preferred embodiment.

The present embodiment is configured to form, as a support column, twosupport columns 103 a and 103 b of wall face structures shown in FIGS.11 (b) and (c) on the lower surface substrate, thereby improving theadhesion force to electrode surfaces (i.e., a scan electrode surface anda signal electrode surface) over that of the second embodiment.

The support column 103 a is configured to have a center part thickerthan that of the support column 102 a. The support column 103 b isconfigured to have a center part thicker than that of the support column102 b. The support column 103 b makes contact with a resin surfacehaving a lower adhesion force to both the lower surface substrate andthe upper surface substrate because it is placed in a gap part betweenthe signal electrode 41 and scan electrode 43, as shown in FIG. 11( a).

The support columns 103 a and 103 b are configured to have a center partthicker than that of the support columns 102 a and 102 b of the secondembodiment, thereby further suppressing the detachment of the supportcolumn in the development process of a photolithography process ascompared to that of the second embodiment.

Meanwhile, an adhesion force of the upper surface substrate to thesupport columns 103 a and 103 b is generated by a pressurized heatingprocess in the adhesive attachment process, the support columns 103 aand 103 b have a lower adhesion force to the resin surface (i.e., theexposed surface of the upper surface substrate). The support columns 103a and 103 b according to the present embodiment are configured to adhereto the signal electrode 41 formed on the upper surface substrate at thecenter of the support columns 103 a and 103 b, thereby improving theoverall adhesion force to the upper surface substrate.

[Fourth Embodiment]

FIG. 12 is a diagram showing a configuration of an LCD element accordingto a fourth preferred embodiment.

As shown in FIGS. 12 (b) and (c), two support columns 104 a and 104 baccording to the present embodiment are configured to modify the form ofthe support column 101 of the first embodiment. The support column 104 ais formed to shorten the branch of the support column 101 in thevertical direction. The support column 104 b is formed to shorten thebranch of the support column 101 in the horizontal direction. Theplacement pattern of the columns 104 a and 104 b are similar to that ofthe support column 101 of the first embodiment (refer to FIG. 7 (a)).

The present embodiment is configured to improve the adhesion force ofthe support columns 104 a and 104 b to (the scan electrode surface of)the lower surface substrate in a similar method to the case of thesecond embodiment, thereby suppressing the detachment of the supportcolumns 104 a and 104 b in the development process of a photolithographyprocess.

The present embodiment is also configured to place the opening parts 45a of the pixels 45 in a zigzag formation so as to suppress the flow-outof the liquid crystal from the inside of the pixel 45 when a pressure isapplied thereto.

[Fifth Embodiment]

FIG. 13 is a diagram showing a configuration of an LCD element accordingto a fifth preferred embodiment.

As shown in FIGS. 13 (b) and (c), two support columns 105 a and 105 b ofthe LCD element according to the present embodiment are configured tomodify the support columns 102 a and 102 b, respectively, of the secondembodiment. The support column 105 a is configured to shorten the branchof the support column 102 a in the vertical direction. The supportcolumn 105 b is configured to shorten the branch of the support column102 b in the horizontal direction. The placement pattern of the supportcolumns 105 a and 105 b is similar to that of the support columns 102 aand 102 b.

The results of an experiment show that it is most effective to have thetip parts of the longer branches be wider when there are differentbranch lengths in the cross form. The present embodiment is anapplication of the result of the experiment.

The present embodiment is configured to place the opening parts 45 a ofthe pixels 45 in a zigzag formation, thereby obtaining a similar effectto that of the fourth embodiment described above.

[Sixth Embodiment]

FIG. 14 is a diagram showing a configuration of an LCD element accordingto a sixth preferred embodiment.

As shown in FIGS. 14 (b) and (c), two support columns 106 a and 106 b ofthe LCD element according to the present embodiment are configured towiden the center parts of the support columns 105 a and 105 b,respectively, of the fifth embodiment, thereby enabling a similar effectto the LCD element of the fifth embodiment. The placement pattern of thesupport columns 106 a and 106 b is similar to the case of the LCDelement of the fifth embodiment as shown in FIG. 13 (a).

Meanwhile, the center part of the support column 106 a is adhered to thescan electrode 43 featured on the lower surface substrate and a surfaceof the signal electrode 41 featured on the upper surface substrate asshown in FIG. 14 (a). Being not specifically shown in a drawing herein,the center part of the support column 106 b is also adhered to the scanelectrode 43 featured on the lower surface substrate and to a surface ofthe signal electrode 41 featured on the upper surface substrate. As aresult of this, the effect of increasing an adhesion force between thelower surface substrate and upper surface substrate is also obtained.

In the aforementioned respective embodiments, the width betweenelectrodes (i.e., between the scan electrode and signal electrode) andthe width of the tip part are set to be 10 micrometers and 30micrometers, respectively, as an example. The margin for the positionalshift of a photolithography process for forming the support column thatis a wall face structure is about plus or minus 5 micrometers, andtherefore the adhesion force is maintained since the tip part is incontact with the electrode surface by way of the air gap between theelectrodes even if the positional shift occurs, provided that the widthof the tip part is about 30 micrometers.

[Seventh Embodiment]

FIG. 15 is a diagram describing a configuration of an LCD elementaccording to a seventh preferred embodiment.

As shown in FIG. 15, the LCD element according to the present embodimentis configured to make a seal structure body formed on the lower surfacesubstrate a triplex structure be constituted by seal structure bodies111 a, 111 b and 111 c, in place of a single seal structure body.

Incidentally, the present embodiment is configured to make the sealstructure bodies consist of three lines; the seal structure bodyaccording to the present invention, however, may consist of a pluralityof lines of no less than two lines, in lieu of being limited to threelines. This is the same for all other embodiments to be described in thefollowing descriptions.

The widths (i.e., the horizontal widths) of the individual sealstructure bodies 111 a, 111 b and 111 c are the same, for example. Thewidths are smaller than the conventional seal structure body 3 shown inFIG. 1, at around 0.001 to 1 mm, for example.

As such, the configuration of a triplex structure constituted by threelines makes it possible to prevent the phenomenon of the gas that isgenerated during the adhesive hardening process in the process formaking the upper and lower surface substrates adhere with each otherremaining in the adhesion surface of the substrate and seal structurebody. The reason is that the gap 113 between the seal structure bodiesis connected to the vicinity of a liquid crystal injection hole 121 sothat the reaction gas of the seal structure body adhesively hardening iseffectively exhausted from the vicinity of the liquid crystal injectionhole, while maintaining the strength of the seal structure body.

Moreover, the seal structure body is constituted by a plurality of linesand therefore, even if some of the lines are cut, the other linesmaintain the seal function, thereby improving the reliability of the LCDelement. If the seal is cut in the process of injecting the liquidcrystal, a seal leakage phenomenon occurs, causing a failure consistingof inability to inject the liquid crystal. The present embodiment isenabled to prevent an occurrence of the seal leakage phenomenon.

[Eighth Embodiment]

FIG. 16 is a partial enlargement diagram of a seal structure bodydescribing a characteristic of an LCD element according to an eighthpreferred embodiment.

A prototype modeling of an LCD element of the seventh embodiment havinga seal structure body of fine lines has resulted in the discovery thatthere is a high probability that the seal structure body will fall overin the development process of a photolithography process for forming theseal structure body, thus resulting in a detachment thereof.

An LCD element according to the eighth embodiment eliminates the problemof the LCD element of the seventh embodiment, and is configured toimprove the adhesion force of the seal structure body to the lowersurface substrate, thereby preventing detachment of the seal structurebody in the photolithography process.

The present embodiment is configured to equip the seal structure bodies111 a, 111 b and 111 c of the seventh embodiment with a plurality ofbranches 211 on both sides of the lines as shown in FIG. 16, in place ofsimple lines. The configuration of the seal structure bodies 111 a, 111b and 111 c having such a line form makes the branches 211 contact withthe lower surface substrate, thus improving the contact area size of theseal structure bodies 111 a, 111 b and 111 c with the lower surfacesubstrate. This configuration makes the seal structure bodies 111 a, 111b and 111 c stable, i.e., they will not fall over easily. This preventsdetachment of the seal structure bodies 111 a, 111 b and 111 c in thedevelopment process of a photolithography process even if their width isconfigured to be small, thereby improving yield in production.

It is further configured to provide gaps 131 in between the respectiveseal structure bodies, with the gaps 131 being connected to the vicinityof the liquid crystal injection hole. This configuration results inexhausting the reactive gas being generated in the gap parts between therespective seal structure bodies from the vicinity of the liquid crystalinjection hole through the gaps 131.

[Ninth Embodiment]

FIG. 17 is a partial enlargement diagram of a seal structure bodyshowing a characteristic of an LCD element according to a ninthpreferred embodiment.

The present embodiment is configured to form the seal structure bodies111 a, 111 b and 111 c in the lines of the repetition of crookedpatterns in the manner of “triangular waves” as shown in FIG. 17,thereby making the seal structure bodies 111 a, 111 b and 111 c not fallover easily.

The respective “triangular waves” parts 221 a, 221 b and 221 c of theseal structure bodies 111 a, 111 b and 111 c are in approximately thesame form and size, nesting each other.

[Tenth Embodiment]

FIG. 18 is a partial enlargement diagram of a seal structure bodydescribing a characteristic of an LCD element according to the tenthembodiment.

The LCD element according to the tenth embodiment is configured to formthe seal structure bodies 111 a, 111 b and 111 c to have convex formedcrooked parts 231 as shown in FIG. 18. The sizes of the convex crookedparts 231 are, in order of size, convex crooked part 231 a of sealstructure body 111 a, convex crooked part 231 b of seal structure body111 b and convex crooked part 231 c of seal structure body 111 c.

The convex crooked part 231 c of seal structure body 111 c is nested inthe convex crooked part 231 b of seal structure body 111 b, and theconvex crooked part 231 b of seal structure body 111 b is nested in theconvex crooked part 231 c of seal structure body 111 a.

The maximum distance between the seal structure body 111 a and sealstructure body 111 c is the same as that between seal structure body 111a and seal structure body 111 c of the eighth embodiment, shown in FIG.15 as an example. The configuration of the eighth through tenthembodiments makes it difficult for the seal structure body to fall overand also improves the strength.

As described above, the aforementioned embodiments are configured tomake the width of a center part or a tip part thicker than the otherparts so that the support column adheres with the electrode surface,thereby improving the adhesion force of the support column to the lowersurface substrate. This configuration makes it possible to suppress theoccurrence of detachment of the support column in the developmentprocess of the photolithography process, forming the pattern of aplurality of support columns even if the horizontal width of the supportcolumn that is a wall face structure body is made smaller. Also, thearea size of only the tip part or center part is larger than the otherparts and therefore a decrease in the opening ratio of the pixel can belimited to a minimum. Incidentally, all of the above embodiments areconfigured to equip all of the four sides of a pixel with an openingpart; the opening of the pixel, however, requires only at least twosides for pixels other than the one located at the edge of the displayarea. The pixel at the edge (e.g., the pixels at the four corners of thedisplay area) may sometimes require only one opening part. Therefore, aconfiguration maybe such that the pixels not positioned at the edge ofthe display area are equipped with opening parts on at least two sides,and such that the tip parts of the adjacent support columns areconnected too close for a pixel that does not necessarily require anopening part.

Further, the form of a pixel in the above embodiments is not necessarilya rectangle.

[Production Method]

Next is an example of a production method for the LCD element of theaforementioned embodiments of the present invention:

(1) Forming a pattern of a scan electrode in a stripe form on the lowersurface substrate.

(2) Forming a film of a wall face material of a few micrometers bycoating the lower surface substrate, which has a pattern of the scanelectrode, with the wall face material that is a photoreceptor.

(3) Exposing the wall face material in an ultraviolet exposure processbyway of a photo mask for forming the support columns and seal structurebody, followed by forming a pattern of the support columns and the sealstructure body by immersing the exposed wall face material in thedevelopment solution.

(4) Coating a seal material, and coating a conventional spherical spaceror forming a columnar spacer, on an as required basis, and forming anoriented film and insulation film on the electrode surface (i.e., thescan electrode surface) on an as required basis.

(5) Adhesively attaching the upper surface substrate, which has astriped electrode pattern (i.e., the signal electrode pattern), and thelower surface substrate, which has a seal structure body and a wall facestructure support column, both of which have been produced by theprocesses of the above paragraphs (1) through (4), so that theelectrodes formed on both of the substrates cross at right angles. Thisis followed by applying the pressurized heating process for an adhesivereaction between the wall face-structured support column and the sealstructure body, and joining the lower surface substrate and uppersurface substrate in a prescribed distance.

(6) Injecting the liquid crystal into the liquid crystal layer furnishedbetween the lower surface substrate and upper surface substrate from theliquid crystal injection hole provided between the lower surfacesubstrate and upper surface substrate; and, upon finishing the injectionof liquid crystal, applying a sealing process for both ends of theliquid crystal layer. It is preferable that the liquid crystal be heatedfor the liquid injection process since the liquid crystal decreases inviscosity with decrease in temperature. An application of pressure iseffective for shortening the time of the liquid crystal injectionprocess.

The above production process eventually completes the LCD element (i.e.,the LCD panel).

The LCD elements of the present embodiments described above can be builtas a display apparatus of an electronic device in the same manner as aconventional LCD element. The LCD elements of the present embodimentsexcel in flexibility and crashworthiness and pressure resistance to thedisplay surface, and are capable of maintaining display performance evenif the display surface is pressed and/or the display part is bent; theyare thus suitable for the display apparatus for an ultra thin electronicdevice such as electronic paper.

Each of the embodiments described above is a dot matrix LCD element; thepresent invention, however, can easily be applied to an active matrixLCD element. The form of the pixel is rectangular according to theembodiments described above; the form of a pixel according to thepresent invention may be different, in lieu of being limited torectangular. Also, each of the above embodiments is configured to form awall face structure body on the scan electrode substrate; the wall facestructure body, however, may be formed on a signal electrode substrate,followed by adhesively attaching a scan electrode substrate.

Furthermore, the present invention is applicable to an LCD elementemploying other liquid crystals having the property of display memory,in addition to a cholesteric LCD element.

The present invention is not limited by the embodiments described above.

What is claimed is:
 1. A liquid crystal display element of a dot matrixstructure comprising: a liquid crystal panel constituted by a firstsubstrate equipped with a first electrode, a second substrate equippedwith a second electrode, and a liquid crystal layer furnished betweenthe first substrate and the second substrate, wherein the liquid crystallayer includes a support column of a wall structure possessingadhesiveness, the support column has a shape approximating a shape of across, a tip part of a branch outward from a center of the cross is awider tip part that is wider than a middle part of the branch, and thewider tip part is more distant than the middle part from the center ofthe cross in a direction along the branch outward from the center. 2.The liquid crystal display element according to claim 1, wherein allbranches of the cross have the wider tip part.
 3. A liquid crystaldisplay element of a dot matrix structure comprising: a liquid crystalpanel constituted by a first substrate equipped with a first electrode,a second substrate equipped with a second electrode, and a liquidcrystal layer furnished between the first substrate and the secondsubstrate, wherein the liquid crystal layer includes a support column ofa wall structure possessing adhesiveness, the support column has a shapeapproximating a shape of a cross, a first tip part of a first branchoutward from a center of the cross is a first wider tip part that iswider than a first middle part of the first branch, the first wider tippart is more distant than the first middle part from the center of thecross in a direction along the first branch outward from the center, asecond tip part of a second branch outward from a center of the cross isa second wider tip part that is wider than a second middle part of thesecond branch, and the second wider tip part is more distant than thesecond middle part from the center of the cross in a direction along thesecond branch outward from the center.
 4. The liquid crystal displayelement according to claim 3, wherein a first center part of the firstbranch is less distant than the first middle part from the center of thecross in the direction along the first branch and wider than the firstmiddle part, and a second center part of the second branch is lessdistant than the second middle part from the center of the cross in thedirection along the second branch and wider than the second middle part.